1 //===-- AddressSanitizer.cpp - memory error detector ------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file is a part of AddressSanitizer, an address sanity checker.
11 // Details of the algorithm:
12 // http://code.google.com/p/address-sanitizer/wiki/AddressSanitizerAlgorithm
14 //===----------------------------------------------------------------------===//
16 #define DEBUG_TYPE "asan"
18 #include "llvm/Transforms/Instrumentation.h"
19 #include "llvm/ADT/ArrayRef.h"
20 #include "llvm/ADT/DenseMap.h"
21 #include "llvm/ADT/DepthFirstIterator.h"
22 #include "llvm/ADT/OwningPtr.h"
23 #include "llvm/ADT/SmallSet.h"
24 #include "llvm/ADT/SmallString.h"
25 #include "llvm/ADT/SmallVector.h"
26 #include "llvm/ADT/StringExtras.h"
27 #include "llvm/ADT/Triple.h"
28 #include "llvm/DIBuilder.h"
29 #include "llvm/IR/DataLayout.h"
30 #include "llvm/IR/Function.h"
31 #include "llvm/IR/IRBuilder.h"
32 #include "llvm/IR/InlineAsm.h"
33 #include "llvm/IR/IntrinsicInst.h"
34 #include "llvm/IR/LLVMContext.h"
35 #include "llvm/IR/Module.h"
36 #include "llvm/IR/Type.h"
37 #include "llvm/InstVisitor.h"
38 #include "llvm/Support/CommandLine.h"
39 #include "llvm/Support/DataTypes.h"
40 #include "llvm/Support/Debug.h"
41 #include "llvm/Support/raw_ostream.h"
42 #include "llvm/Support/system_error.h"
43 #include "llvm/Target/TargetMachine.h"
44 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
45 #include "llvm/Transforms/Utils/BlackList.h"
46 #include "llvm/Transforms/Utils/Local.h"
47 #include "llvm/Transforms/Utils/ModuleUtils.h"
53 static const uint64_t kDefaultShadowScale = 3;
54 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
55 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
56 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
58 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
59 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
60 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
62 static const char *kAsanModuleCtorName = "asan.module_ctor";
63 static const char *kAsanModuleDtorName = "asan.module_dtor";
64 static const int kAsanCtorAndCtorPriority = 1;
65 static const char *kAsanReportErrorTemplate = "__asan_report_";
66 static const char *kAsanRegisterGlobalsName = "__asan_register_globals";
67 static const char *kAsanUnregisterGlobalsName = "__asan_unregister_globals";
68 static const char *kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
69 static const char *kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
70 static const char *kAsanInitName = "__asan_init";
71 static const char *kAsanHandleNoReturnName = "__asan_handle_no_return";
72 static const char *kAsanMappingOffsetName = "__asan_mapping_offset";
73 static const char *kAsanMappingScaleName = "__asan_mapping_scale";
74 static const char *kAsanStackMallocName = "__asan_stack_malloc";
75 static const char *kAsanStackFreeName = "__asan_stack_free";
76 static const char *kAsanGenPrefix = "__asan_gen_";
77 static const char *kAsanPoisonStackMemoryName = "__asan_poison_stack_memory";
78 static const char *kAsanUnpoisonStackMemoryName =
79 "__asan_unpoison_stack_memory";
81 static const int kAsanStackLeftRedzoneMagic = 0xf1;
82 static const int kAsanStackMidRedzoneMagic = 0xf2;
83 static const int kAsanStackRightRedzoneMagic = 0xf3;
84 static const int kAsanStackPartialRedzoneMagic = 0xf4;
86 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
87 static const size_t kNumberOfAccessSizes = 5;
89 // Command-line flags.
91 // This flag may need to be replaced with -f[no-]asan-reads.
92 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
93 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
94 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
95 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
96 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
97 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
98 cl::Hidden, cl::init(true));
99 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
100 cl::desc("use instrumentation with slow path for all accesses"),
101 cl::Hidden, cl::init(false));
102 // This flag limits the number of instructions to be instrumented
103 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
104 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
106 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
108 cl::desc("maximal number of instructions to instrument in any given BB"),
110 // This flag may need to be replaced with -f[no]asan-stack.
111 static cl::opt<bool> ClStack("asan-stack",
112 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
113 // This flag may need to be replaced with -f[no]asan-use-after-return.
114 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
115 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
116 // This flag may need to be replaced with -f[no]asan-globals.
117 static cl::opt<bool> ClGlobals("asan-globals",
118 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
119 static cl::opt<bool> ClInitializers("asan-initialization-order",
120 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
121 static cl::opt<bool> ClMemIntrin("asan-memintrin",
122 cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
123 static cl::opt<bool> ClRealignStack("asan-realign-stack",
124 cl::desc("Realign stack to 32"), cl::Hidden, cl::init(true));
125 static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
126 cl::desc("File containing the list of objects to ignore "
127 "during instrumentation"), cl::Hidden);
129 // These flags allow to change the shadow mapping.
130 // The shadow mapping looks like
131 // Shadow = (Mem >> scale) + (1 << offset_log)
132 static cl::opt<int> ClMappingScale("asan-mapping-scale",
133 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
134 static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
135 cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
137 // Optimization flags. Not user visible, used mostly for testing
138 // and benchmarking the tool.
139 static cl::opt<bool> ClOpt("asan-opt",
140 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
141 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
142 cl::desc("Instrument the same temp just once"), cl::Hidden,
144 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
145 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
147 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
148 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
149 cl::Hidden, cl::init(false));
152 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
154 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
155 cl::Hidden, cl::init(0));
156 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
157 cl::Hidden, cl::desc("Debug func"));
158 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
159 cl::Hidden, cl::init(-1));
160 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
161 cl::Hidden, cl::init(-1));
164 /// A set of dynamically initialized globals extracted from metadata.
165 class SetOfDynamicallyInitializedGlobals {
167 void Init(Module& M) {
168 // Clang generates metadata identifying all dynamically initialized globals.
169 NamedMDNode *DynamicGlobals =
170 M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
173 for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
174 MDNode *MDN = DynamicGlobals->getOperand(i);
175 assert(MDN->getNumOperands() == 1);
176 Value *VG = MDN->getOperand(0);
177 // The optimizer may optimize away a global entirely, in which case we
178 // cannot instrument access to it.
181 DynInitGlobals.insert(cast<GlobalVariable>(VG));
184 bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
186 SmallSet<GlobalValue*, 32> DynInitGlobals;
189 /// This struct defines the shadow mapping using the rule:
190 /// shadow = (mem >> Scale) ADD-or-OR Offset.
191 struct ShadowMapping {
197 static ShadowMapping getShadowMapping(const Module &M, int LongSize,
198 bool ZeroBaseShadow) {
199 llvm::Triple TargetTriple(M.getTargetTriple());
200 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
201 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64;
203 ShadowMapping Mapping;
205 // OR-ing shadow offset if more efficient (at least on x86),
206 // but on ppc64 we have to use add since the shadow offset is not neccesary
207 // 1/8-th of the address space.
208 Mapping.OrShadowOffset = !IsPPC64;
210 Mapping.Offset = (IsAndroid || ZeroBaseShadow) ? 0 :
211 (LongSize == 32 ? kDefaultShadowOffset32 :
212 IsPPC64 ? kPPC64_ShadowOffset64 : kDefaultShadowOffset64);
213 if (ClMappingOffsetLog >= 0) {
214 // Zero offset log is the special case.
215 Mapping.Offset = (ClMappingOffsetLog == 0) ? 0 : 1ULL << ClMappingOffsetLog;
218 Mapping.Scale = kDefaultShadowScale;
219 if (ClMappingScale) {
220 Mapping.Scale = ClMappingScale;
226 static size_t RedzoneSizeForScale(int MappingScale) {
227 // Redzone used for stack and globals is at least 32 bytes.
228 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
229 return std::max(32U, 1U << MappingScale);
232 /// AddressSanitizer: instrument the code in module to find memory bugs.
233 struct AddressSanitizer : public FunctionPass {
234 AddressSanitizer(bool CheckInitOrder = false,
235 bool CheckUseAfterReturn = false,
236 bool CheckLifetime = false,
237 StringRef BlacklistFile = StringRef(),
238 bool ZeroBaseShadow = false)
240 CheckInitOrder(CheckInitOrder || ClInitializers),
241 CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
242 CheckLifetime(CheckLifetime || ClCheckLifetime),
243 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
245 ZeroBaseShadow(ZeroBaseShadow) {}
246 virtual const char *getPassName() const {
247 return "AddressSanitizerFunctionPass";
249 void instrumentMop(Instruction *I);
250 void instrumentAddress(Instruction *OrigIns, IRBuilder<> &IRB,
251 Value *Addr, uint32_t TypeSize, bool IsWrite);
252 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
253 Value *ShadowValue, uint32_t TypeSize);
254 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
255 bool IsWrite, size_t AccessSizeIndex);
256 bool instrumentMemIntrinsic(MemIntrinsic *MI);
257 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
259 Instruction *InsertBefore, bool IsWrite);
260 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
261 bool runOnFunction(Function &F);
262 void createInitializerPoisonCalls(Module &M,
263 Value *FirstAddr, Value *LastAddr);
264 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
265 void emitShadowMapping(Module &M, IRBuilder<> &IRB) const;
266 virtual bool doInitialization(Module &M);
267 static char ID; // Pass identification, replacement for typeid
270 void initializeCallbacks(Module &M);
272 bool ShouldInstrumentGlobal(GlobalVariable *G);
273 bool LooksLikeCodeInBug11395(Instruction *I);
274 void FindDynamicInitializers(Module &M);
277 bool CheckUseAfterReturn;
279 SmallString<64> BlacklistFile;
286 ShadowMapping Mapping;
287 Function *AsanCtorFunction;
288 Function *AsanInitFunction;
289 Function *AsanHandleNoReturnFunc;
290 OwningPtr<BlackList> BL;
291 // This array is indexed by AccessIsWrite and log2(AccessSize).
292 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
294 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
296 friend struct FunctionStackPoisoner;
299 class AddressSanitizerModule : public ModulePass {
301 AddressSanitizerModule(bool CheckInitOrder = false,
302 StringRef BlacklistFile = StringRef(),
303 bool ZeroBaseShadow = false)
305 CheckInitOrder(CheckInitOrder || ClInitializers),
306 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
308 ZeroBaseShadow(ZeroBaseShadow) {}
309 bool runOnModule(Module &M);
310 static char ID; // Pass identification, replacement for typeid
311 virtual const char *getPassName() const {
312 return "AddressSanitizerModule";
316 void initializeCallbacks(Module &M);
318 bool ShouldInstrumentGlobal(GlobalVariable *G);
319 void createInitializerPoisonCalls(Module &M, Value *FirstAddr,
321 size_t RedzoneSize() const {
322 return RedzoneSizeForScale(Mapping.Scale);
326 SmallString<64> BlacklistFile;
329 OwningPtr<BlackList> BL;
330 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
334 ShadowMapping Mapping;
335 Function *AsanPoisonGlobals;
336 Function *AsanUnpoisonGlobals;
337 Function *AsanRegisterGlobals;
338 Function *AsanUnregisterGlobals;
341 // Stack poisoning does not play well with exception handling.
342 // When an exception is thrown, we essentially bypass the code
343 // that unpoisones the stack. This is why the run-time library has
344 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
345 // stack in the interceptor. This however does not work inside the
346 // actual function which catches the exception. Most likely because the
347 // compiler hoists the load of the shadow value somewhere too high.
348 // This causes asan to report a non-existing bug on 453.povray.
349 // It sounds like an LLVM bug.
350 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
352 AddressSanitizer &ASan;
357 ShadowMapping Mapping;
359 SmallVector<AllocaInst*, 16> AllocaVec;
360 SmallVector<Instruction*, 8> RetVec;
361 uint64_t TotalStackSize;
362 unsigned StackAlignment;
364 Function *AsanStackMallocFunc, *AsanStackFreeFunc;
365 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
367 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
368 struct AllocaPoisonCall {
369 IntrinsicInst *InsBefore;
373 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
375 // Maps Value to an AllocaInst from which the Value is originated.
376 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
377 AllocaForValueMapTy AllocaForValue;
379 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
380 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
381 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
382 Mapping(ASan.Mapping),
383 TotalStackSize(0), StackAlignment(1 << Mapping.Scale) {}
385 bool runOnFunction() {
386 if (!ClStack) return false;
387 // Collect alloca, ret, lifetime instructions etc.
388 for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
389 DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
390 BasicBlock *BB = *DI;
393 if (AllocaVec.empty()) return false;
395 initializeCallbacks(*F.getParent());
405 // Finds all static Alloca instructions and puts
406 // poisoned red zones around all of them.
407 // Then unpoison everything back before the function returns.
410 // ----------------------- Visitors.
411 /// \brief Collect all Ret instructions.
412 void visitReturnInst(ReturnInst &RI) {
413 RetVec.push_back(&RI);
416 /// \brief Collect Alloca instructions we want (and can) handle.
417 void visitAllocaInst(AllocaInst &AI) {
418 if (!isInterestingAlloca(AI)) return;
420 StackAlignment = std::max(StackAlignment, AI.getAlignment());
421 AllocaVec.push_back(&AI);
422 uint64_t AlignedSize = getAlignedAllocaSize(&AI);
423 TotalStackSize += AlignedSize;
426 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
428 void visitIntrinsicInst(IntrinsicInst &II) {
429 if (!ASan.CheckLifetime) return;
430 Intrinsic::ID ID = II.getIntrinsicID();
431 if (ID != Intrinsic::lifetime_start &&
432 ID != Intrinsic::lifetime_end)
434 // Found lifetime intrinsic, add ASan instrumentation if necessary.
435 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
436 // If size argument is undefined, don't do anything.
437 if (Size->isMinusOne()) return;
438 // Check that size doesn't saturate uint64_t and can
439 // be stored in IntptrTy.
440 const uint64_t SizeValue = Size->getValue().getLimitedValue();
441 if (SizeValue == ~0ULL ||
442 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
444 // Find alloca instruction that corresponds to llvm.lifetime argument.
445 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
447 bool DoPoison = (ID == Intrinsic::lifetime_end);
448 AllocaPoisonCall APC = {&II, SizeValue, DoPoison};
449 AllocaPoisonCallVec.push_back(APC);
452 // ---------------------- Helpers.
453 void initializeCallbacks(Module &M);
455 // Check if we want (and can) handle this alloca.
456 bool isInterestingAlloca(AllocaInst &AI) {
457 return (!AI.isArrayAllocation() &&
458 AI.isStaticAlloca() &&
459 AI.getAllocatedType()->isSized());
462 size_t RedzoneSize() const {
463 return RedzoneSizeForScale(Mapping.Scale);
465 uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
466 Type *Ty = AI->getAllocatedType();
467 uint64_t SizeInBytes = ASan.TD->getTypeAllocSize(Ty);
470 uint64_t getAlignedSize(uint64_t SizeInBytes) {
471 size_t RZ = RedzoneSize();
472 return ((SizeInBytes + RZ - 1) / RZ) * RZ;
474 uint64_t getAlignedAllocaSize(AllocaInst *AI) {
475 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
476 return getAlignedSize(SizeInBytes);
478 /// Finds alloca where the value comes from.
479 AllocaInst *findAllocaForValue(Value *V);
480 void poisonRedZones(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
481 Value *ShadowBase, bool DoPoison);
482 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> IRB, bool DoPoison);
487 char AddressSanitizer::ID = 0;
488 INITIALIZE_PASS(AddressSanitizer, "asan",
489 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
491 FunctionPass *llvm::createAddressSanitizerFunctionPass(
492 bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
493 StringRef BlacklistFile, bool ZeroBaseShadow) {
494 return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
495 CheckLifetime, BlacklistFile, ZeroBaseShadow);
498 char AddressSanitizerModule::ID = 0;
499 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
500 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
501 "ModulePass", false, false)
502 ModulePass *llvm::createAddressSanitizerModulePass(
503 bool CheckInitOrder, StringRef BlacklistFile, bool ZeroBaseShadow) {
504 return new AddressSanitizerModule(CheckInitOrder, BlacklistFile,
508 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
509 size_t Res = CountTrailingZeros_32(TypeSize / 8);
510 assert(Res < kNumberOfAccessSizes);
514 // Create a constant for Str so that we can pass it to the run-time lib.
515 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
516 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
517 return new GlobalVariable(M, StrConst->getType(), true,
518 GlobalValue::PrivateLinkage, StrConst,
522 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
523 return G->getName().find(kAsanGenPrefix) == 0;
526 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
528 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
529 if (Mapping.Offset == 0)
531 // (Shadow >> scale) | offset
532 if (Mapping.OrShadowOffset)
533 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
535 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
538 void AddressSanitizer::instrumentMemIntrinsicParam(
539 Instruction *OrigIns,
540 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
541 // Check the first byte.
543 IRBuilder<> IRB(InsertBefore);
544 instrumentAddress(OrigIns, IRB, Addr, 8, IsWrite);
546 // Check the last byte.
548 IRBuilder<> IRB(InsertBefore);
549 Value *SizeMinusOne = IRB.CreateSub(
550 Size, ConstantInt::get(Size->getType(), 1));
551 SizeMinusOne = IRB.CreateIntCast(SizeMinusOne, IntptrTy, false);
552 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
553 Value *AddrPlusSizeMinisOne = IRB.CreateAdd(AddrLong, SizeMinusOne);
554 instrumentAddress(OrigIns, IRB, AddrPlusSizeMinisOne, 8, IsWrite);
558 // Instrument memset/memmove/memcpy
559 bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
560 Value *Dst = MI->getDest();
561 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
562 Value *Src = MemTran ? MemTran->getSource() : 0;
563 Value *Length = MI->getLength();
565 Constant *ConstLength = dyn_cast<Constant>(Length);
566 Instruction *InsertBefore = MI;
568 if (ConstLength->isNullValue()) return false;
570 // The size is not a constant so it could be zero -- check at run-time.
571 IRBuilder<> IRB(InsertBefore);
573 Value *Cmp = IRB.CreateICmpNE(Length,
574 Constant::getNullValue(Length->getType()));
575 InsertBefore = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
578 instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
580 instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
584 // If I is an interesting memory access, return the PointerOperand
585 // and set IsWrite. Otherwise return NULL.
586 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
587 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
588 if (!ClInstrumentReads) return NULL;
590 return LI->getPointerOperand();
592 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
593 if (!ClInstrumentWrites) return NULL;
595 return SI->getPointerOperand();
597 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
598 if (!ClInstrumentAtomics) return NULL;
600 return RMW->getPointerOperand();
602 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
603 if (!ClInstrumentAtomics) return NULL;
605 return XCHG->getPointerOperand();
610 void AddressSanitizer::instrumentMop(Instruction *I) {
611 bool IsWrite = false;
612 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
614 if (ClOpt && ClOptGlobals) {
615 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
616 // If initialization order checking is disabled, a simple access to a
617 // dynamically initialized global is always valid.
620 // If a global variable does not have dynamic initialization we don't
621 // have to instrument it. However, if a global does not have initailizer
622 // at all, we assume it has dynamic initializer (in other TU).
623 if (G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G))
628 Type *OrigPtrTy = Addr->getType();
629 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
631 assert(OrigTy->isSized());
632 uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
634 if (TypeSize != 8 && TypeSize != 16 &&
635 TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
636 // Ignore all unusual sizes.
641 instrumentAddress(I, IRB, Addr, TypeSize, IsWrite);
644 // Validate the result of Module::getOrInsertFunction called for an interface
645 // function of AddressSanitizer. If the instrumented module defines a function
646 // with the same name, their prototypes must match, otherwise
647 // getOrInsertFunction returns a bitcast.
648 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
649 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
650 FuncOrBitcast->dump();
651 report_fatal_error("trying to redefine an AddressSanitizer "
652 "interface function");
655 Instruction *AddressSanitizer::generateCrashCode(
656 Instruction *InsertBefore, Value *Addr,
657 bool IsWrite, size_t AccessSizeIndex) {
658 IRBuilder<> IRB(InsertBefore);
659 CallInst *Call = IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex],
661 // We don't do Call->setDoesNotReturn() because the BB already has
662 // UnreachableInst at the end.
663 // This EmptyAsm is required to avoid callback merge.
664 IRB.CreateCall(EmptyAsm);
668 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
671 size_t Granularity = 1 << Mapping.Scale;
672 // Addr & (Granularity - 1)
673 Value *LastAccessedByte = IRB.CreateAnd(
674 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
675 // (Addr & (Granularity - 1)) + size - 1
676 if (TypeSize / 8 > 1)
677 LastAccessedByte = IRB.CreateAdd(
678 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
679 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
680 LastAccessedByte = IRB.CreateIntCast(
681 LastAccessedByte, ShadowValue->getType(), false);
682 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
683 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
686 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
687 IRBuilder<> &IRB, Value *Addr,
688 uint32_t TypeSize, bool IsWrite) {
689 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
691 Type *ShadowTy = IntegerType::get(
692 *C, std::max(8U, TypeSize >> Mapping.Scale));
693 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
694 Value *ShadowPtr = memToShadow(AddrLong, IRB);
695 Value *CmpVal = Constant::getNullValue(ShadowTy);
696 Value *ShadowValue = IRB.CreateLoad(
697 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
699 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
700 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
701 size_t Granularity = 1 << Mapping.Scale;
702 TerminatorInst *CrashTerm = 0;
704 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
705 TerminatorInst *CheckTerm =
706 SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
707 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
708 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
709 IRB.SetInsertPoint(CheckTerm);
710 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
711 BasicBlock *CrashBlock =
712 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
713 CrashTerm = new UnreachableInst(*C, CrashBlock);
714 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
715 ReplaceInstWithInst(CheckTerm, NewTerm);
717 CrashTerm = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), true);
721 generateCrashCode(CrashTerm, AddrLong, IsWrite, AccessSizeIndex);
722 Crash->setDebugLoc(OrigIns->getDebugLoc());
725 void AddressSanitizerModule::createInitializerPoisonCalls(
726 Module &M, Value *FirstAddr, Value *LastAddr) {
727 // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
728 Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
729 // If that function is not present, this TU contains no globals, or they have
730 // all been optimized away
734 // Set up the arguments to our poison/unpoison functions.
735 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
737 // Add a call to poison all external globals before the given function starts.
738 IRB.CreateCall2(AsanPoisonGlobals, FirstAddr, LastAddr);
740 // Add calls to unpoison all globals before each return instruction.
741 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
743 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
744 CallInst::Create(AsanUnpoisonGlobals, "", RI);
749 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
750 Type *Ty = cast<PointerType>(G->getType())->getElementType();
751 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
753 if (BL->isIn(*G)) return false;
754 if (!Ty->isSized()) return false;
755 if (!G->hasInitializer()) return false;
756 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
757 // Touch only those globals that will not be defined in other modules.
758 // Don't handle ODR type linkages since other modules may be built w/o asan.
759 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
760 G->getLinkage() != GlobalVariable::PrivateLinkage &&
761 G->getLinkage() != GlobalVariable::InternalLinkage)
763 // Two problems with thread-locals:
764 // - The address of the main thread's copy can't be computed at link-time.
765 // - Need to poison all copies, not just the main thread's one.
766 if (G->isThreadLocal())
768 // For now, just ignore this Alloca if the alignment is large.
769 if (G->getAlignment() > RedzoneSize()) return false;
771 // Ignore all the globals with the names starting with "\01L_OBJC_".
772 // Many of those are put into the .cstring section. The linker compresses
773 // that section by removing the spare \0s after the string terminator, so
774 // our redzones get broken.
775 if ((G->getName().find("\01L_OBJC_") == 0) ||
776 (G->getName().find("\01l_OBJC_") == 0)) {
777 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
781 if (G->hasSection()) {
782 StringRef Section(G->getSection());
783 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
784 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
786 if ((Section.find("__OBJC,") == 0) ||
787 (Section.find("__DATA, __objc_") == 0)) {
788 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
791 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
792 // Constant CFString instances are compiled in the following way:
793 // -- the string buffer is emitted into
794 // __TEXT,__cstring,cstring_literals
795 // -- the constant NSConstantString structure referencing that buffer
796 // is placed into __DATA,__cfstring
797 // Therefore there's no point in placing redzones into __DATA,__cfstring.
798 // Moreover, it causes the linker to crash on OS X 10.7
799 if (Section.find("__DATA,__cfstring") == 0) {
800 DEBUG(dbgs() << "Ignoring CFString: " << *G);
808 void AddressSanitizerModule::initializeCallbacks(Module &M) {
810 // Declare our poisoning and unpoisoning functions.
811 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
812 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
813 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
814 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
815 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
816 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
817 // Declare functions that register/unregister globals.
818 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
819 kAsanRegisterGlobalsName, IRB.getVoidTy(),
820 IntptrTy, IntptrTy, NULL));
821 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
822 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
823 kAsanUnregisterGlobalsName,
824 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
825 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
828 // This function replaces all global variables with new variables that have
829 // trailing redzones. It also creates a function that poisons
830 // redzones and inserts this function into llvm.global_ctors.
831 bool AddressSanitizerModule::runOnModule(Module &M) {
832 if (!ClGlobals) return false;
833 TD = getAnalysisIfAvailable<DataLayout>();
836 BL.reset(new BlackList(BlacklistFile));
837 if (BL->isIn(M)) return false;
838 C = &(M.getContext());
839 int LongSize = TD->getPointerSizeInBits();
840 IntptrTy = Type::getIntNTy(*C, LongSize);
841 Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
842 initializeCallbacks(M);
843 DynamicallyInitializedGlobals.Init(M);
845 SmallVector<GlobalVariable *, 16> GlobalsToChange;
847 for (Module::GlobalListType::iterator G = M.global_begin(),
848 E = M.global_end(); G != E; ++G) {
849 if (ShouldInstrumentGlobal(G))
850 GlobalsToChange.push_back(G);
853 size_t n = GlobalsToChange.size();
854 if (n == 0) return false;
856 // A global is described by a structure
859 // size_t size_with_redzone;
861 // size_t has_dynamic_init;
862 // We initialize an array of such structures and pass it to a run-time call.
863 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
866 SmallVector<Constant *, 16> Initializers(n), DynamicInit;
869 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
871 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
873 // The addresses of the first and last dynamically initialized globals in
874 // this TU. Used in initialization order checking.
875 Value *FirstDynamic = 0, *LastDynamic = 0;
877 for (size_t i = 0; i < n; i++) {
878 GlobalVariable *G = GlobalsToChange[i];
879 PointerType *PtrTy = cast<PointerType>(G->getType());
880 Type *Ty = PtrTy->getElementType();
881 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
882 size_t RZ = RedzoneSize();
883 uint64_t RightRedzoneSize = RZ + (RZ - (SizeInBytes % RZ));
884 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
885 // Determine whether this global should be poisoned in initialization.
886 bool GlobalHasDynamicInitializer =
887 DynamicallyInitializedGlobals.Contains(G);
888 // Don't check initialization order if this global is blacklisted.
889 GlobalHasDynamicInitializer &= !BL->isInInit(*G);
891 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
892 Constant *NewInitializer = ConstantStruct::get(
893 NewTy, G->getInitializer(),
894 Constant::getNullValue(RightRedZoneTy), NULL);
896 SmallString<2048> DescriptionOfGlobal = G->getName();
897 DescriptionOfGlobal += " (";
898 DescriptionOfGlobal += M.getModuleIdentifier();
899 DescriptionOfGlobal += ")";
900 GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal);
902 // Create a new global variable with enough space for a redzone.
903 GlobalVariable *NewGlobal = new GlobalVariable(
904 M, NewTy, G->isConstant(), G->getLinkage(),
905 NewInitializer, "", G, G->getThreadLocalMode());
906 NewGlobal->copyAttributesFrom(G);
907 NewGlobal->setAlignment(RZ);
910 Indices2[0] = IRB.getInt32(0);
911 Indices2[1] = IRB.getInt32(0);
913 G->replaceAllUsesWith(
914 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
915 NewGlobal->takeName(G);
916 G->eraseFromParent();
918 Initializers[i] = ConstantStruct::get(
920 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
921 ConstantInt::get(IntptrTy, SizeInBytes),
922 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
923 ConstantExpr::getPointerCast(Name, IntptrTy),
924 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
927 // Populate the first and last globals declared in this TU.
928 if (CheckInitOrder && GlobalHasDynamicInitializer) {
929 LastDynamic = ConstantExpr::getPointerCast(NewGlobal, IntptrTy);
930 if (FirstDynamic == 0)
931 FirstDynamic = LastDynamic;
934 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
937 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
938 GlobalVariable *AllGlobals = new GlobalVariable(
939 M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
940 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
942 // Create calls for poisoning before initializers run and unpoisoning after.
943 if (CheckInitOrder && FirstDynamic && LastDynamic)
944 createInitializerPoisonCalls(M, FirstDynamic, LastDynamic);
945 IRB.CreateCall2(AsanRegisterGlobals,
946 IRB.CreatePointerCast(AllGlobals, IntptrTy),
947 ConstantInt::get(IntptrTy, n));
949 // We also need to unregister globals at the end, e.g. when a shared library
951 Function *AsanDtorFunction = Function::Create(
952 FunctionType::get(Type::getVoidTy(*C), false),
953 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
954 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
955 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
956 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
957 IRB.CreatePointerCast(AllGlobals, IntptrTy),
958 ConstantInt::get(IntptrTy, n));
959 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
965 void AddressSanitizer::initializeCallbacks(Module &M) {
967 // Create __asan_report* callbacks.
968 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
969 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
971 // IsWrite and TypeSize are encoded in the function name.
972 std::string FunctionName = std::string(kAsanReportErrorTemplate) +
973 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
974 // If we are merging crash callbacks, they have two parameters.
975 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
976 checkInterfaceFunction(M.getOrInsertFunction(
977 FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
981 AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
982 kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
983 // We insert an empty inline asm after __asan_report* to avoid callback merge.
984 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
985 StringRef(""), StringRef(""),
986 /*hasSideEffects=*/true);
989 void AddressSanitizer::emitShadowMapping(Module &M, IRBuilder<> &IRB) const {
990 // Tell the values of mapping offset and scale to the run-time.
991 GlobalValue *asan_mapping_offset =
992 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
993 ConstantInt::get(IntptrTy, Mapping.Offset),
994 kAsanMappingOffsetName);
995 // Read the global, otherwise it may be optimized away.
996 IRB.CreateLoad(asan_mapping_offset, true);
998 GlobalValue *asan_mapping_scale =
999 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1000 ConstantInt::get(IntptrTy, Mapping.Scale),
1001 kAsanMappingScaleName);
1002 // Read the global, otherwise it may be optimized away.
1003 IRB.CreateLoad(asan_mapping_scale, true);
1007 bool AddressSanitizer::doInitialization(Module &M) {
1008 // Initialize the private fields. No one has accessed them before.
1009 TD = getAnalysisIfAvailable<DataLayout>();
1013 BL.reset(new BlackList(BlacklistFile));
1014 DynamicallyInitializedGlobals.Init(M);
1016 C = &(M.getContext());
1017 LongSize = TD->getPointerSizeInBits();
1018 IntptrTy = Type::getIntNTy(*C, LongSize);
1020 AsanCtorFunction = Function::Create(
1021 FunctionType::get(Type::getVoidTy(*C), false),
1022 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1023 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1024 // call __asan_init in the module ctor.
1025 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1026 AsanInitFunction = checkInterfaceFunction(
1027 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1028 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1029 IRB.CreateCall(AsanInitFunction);
1031 Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
1032 emitShadowMapping(M, IRB);
1034 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
1038 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1039 // For each NSObject descendant having a +load method, this method is invoked
1040 // by the ObjC runtime before any of the static constructors is called.
1041 // Therefore we need to instrument such methods with a call to __asan_init
1042 // at the beginning in order to initialize our runtime before any access to
1043 // the shadow memory.
1044 // We cannot just ignore these methods, because they may call other
1045 // instrumented functions.
1046 if (F.getName().find(" load]") != std::string::npos) {
1047 IRBuilder<> IRB(F.begin()->begin());
1048 IRB.CreateCall(AsanInitFunction);
1054 bool AddressSanitizer::runOnFunction(Function &F) {
1055 if (BL->isIn(F)) return false;
1056 if (&F == AsanCtorFunction) return false;
1057 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1058 initializeCallbacks(*F.getParent());
1060 // If needed, insert __asan_init before checking for AddressSafety attr.
1061 maybeInsertAsanInitAtFunctionEntry(F);
1063 if (!F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
1064 Attribute::AddressSafety))
1067 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1070 // We want to instrument every address only once per basic block (unless there
1071 // are calls between uses).
1072 SmallSet<Value*, 16> TempsToInstrument;
1073 SmallVector<Instruction*, 16> ToInstrument;
1074 SmallVector<Instruction*, 8> NoReturnCalls;
1077 // Fill the set of memory operations to instrument.
1078 for (Function::iterator FI = F.begin(), FE = F.end();
1080 TempsToInstrument.clear();
1081 int NumInsnsPerBB = 0;
1082 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1084 if (LooksLikeCodeInBug11395(BI)) return false;
1085 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
1086 if (ClOpt && ClOptSameTemp) {
1087 if (!TempsToInstrument.insert(Addr))
1088 continue; // We've seen this temp in the current BB.
1090 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
1093 if (CallInst *CI = dyn_cast<CallInst>(BI)) {
1094 // A call inside BB.
1095 TempsToInstrument.clear();
1096 if (CI->doesNotReturn()) {
1097 NoReturnCalls.push_back(CI);
1102 ToInstrument.push_back(BI);
1104 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1110 int NumInstrumented = 0;
1111 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1112 Instruction *Inst = ToInstrument[i];
1113 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1114 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1115 if (isInterestingMemoryAccess(Inst, &IsWrite))
1116 instrumentMop(Inst);
1118 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1123 FunctionStackPoisoner FSP(F, *this);
1124 bool ChangedStack = FSP.runOnFunction();
1126 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1127 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1128 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1129 Instruction *CI = NoReturnCalls[i];
1130 IRBuilder<> IRB(CI);
1131 IRB.CreateCall(AsanHandleNoReturnFunc);
1133 DEBUG(dbgs() << "ASAN done instrumenting:\n" << F << "\n");
1135 return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1138 static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
1139 if (ShadowRedzoneSize == 1) return PoisonByte;
1140 if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
1141 if (ShadowRedzoneSize == 4)
1142 return (PoisonByte << 24) + (PoisonByte << 16) +
1143 (PoisonByte << 8) + (PoisonByte);
1144 llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
1147 static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
1150 size_t ShadowGranularity,
1152 for (size_t i = 0; i < RZSize;
1153 i+= ShadowGranularity, Shadow++) {
1154 if (i + ShadowGranularity <= Size) {
1155 *Shadow = 0; // fully addressable
1156 } else if (i >= Size) {
1157 *Shadow = Magic; // unaddressable
1159 *Shadow = Size - i; // first Size-i bytes are addressable
1164 // Workaround for bug 11395: we don't want to instrument stack in functions
1165 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1166 // FIXME: remove once the bug 11395 is fixed.
1167 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1168 if (LongSize != 32) return false;
1169 CallInst *CI = dyn_cast<CallInst>(I);
1170 if (!CI || !CI->isInlineAsm()) return false;
1171 if (CI->getNumArgOperands() <= 5) return false;
1172 // We have inline assembly with quite a few arguments.
1176 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1177 IRBuilder<> IRB(*C);
1178 AsanStackMallocFunc = checkInterfaceFunction(M.getOrInsertFunction(
1179 kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL));
1180 AsanStackFreeFunc = checkInterfaceFunction(M.getOrInsertFunction(
1181 kAsanStackFreeName, IRB.getVoidTy(),
1182 IntptrTy, IntptrTy, IntptrTy, NULL));
1183 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1184 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1185 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1186 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1189 void FunctionStackPoisoner::poisonRedZones(
1190 const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB, Value *ShadowBase,
1192 size_t ShadowRZSize = RedzoneSize() >> Mapping.Scale;
1193 assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
1194 Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
1195 Type *RZPtrTy = PointerType::get(RZTy, 0);
1197 Value *PoisonLeft = ConstantInt::get(RZTy,
1198 ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
1199 Value *PoisonMid = ConstantInt::get(RZTy,
1200 ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
1201 Value *PoisonRight = ConstantInt::get(RZTy,
1202 ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
1204 // poison the first red zone.
1205 IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
1207 // poison all other red zones.
1208 uint64_t Pos = RedzoneSize();
1209 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1210 AllocaInst *AI = AllocaVec[i];
1211 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1212 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1213 assert(AlignedSize - SizeInBytes < RedzoneSize());
1218 assert(ShadowBase->getType() == IntptrTy);
1219 if (SizeInBytes < AlignedSize) {
1220 // Poison the partial redzone at right
1221 Ptr = IRB.CreateAdd(
1222 ShadowBase, ConstantInt::get(IntptrTy,
1223 (Pos >> Mapping.Scale) - ShadowRZSize));
1224 size_t AddressableBytes = RedzoneSize() - (AlignedSize - SizeInBytes);
1225 uint32_t Poison = 0;
1227 PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
1229 1ULL << Mapping.Scale,
1230 kAsanStackPartialRedzoneMagic);
1232 Value *PartialPoison = ConstantInt::get(RZTy, Poison);
1233 IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1236 // Poison the full redzone at right.
1237 Ptr = IRB.CreateAdd(ShadowBase,
1238 ConstantInt::get(IntptrTy, Pos >> Mapping.Scale));
1239 bool LastAlloca = (i == AllocaVec.size() - 1);
1240 Value *Poison = LastAlloca ? PoisonRight : PoisonMid;
1241 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1243 Pos += RedzoneSize();
1247 void FunctionStackPoisoner::poisonStack() {
1248 uint64_t LocalStackSize = TotalStackSize +
1249 (AllocaVec.size() + 1) * RedzoneSize();
1251 bool DoStackMalloc = ASan.CheckUseAfterReturn
1252 && LocalStackSize <= kMaxStackMallocSize;
1254 assert(AllocaVec.size() > 0);
1255 Instruction *InsBefore = AllocaVec[0];
1256 IRBuilder<> IRB(InsBefore);
1259 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1260 AllocaInst *MyAlloca =
1261 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1262 if (ClRealignStack && StackAlignment < RedzoneSize())
1263 StackAlignment = RedzoneSize();
1264 MyAlloca->setAlignment(StackAlignment);
1265 assert(MyAlloca->isStaticAlloca());
1266 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1267 Value *LocalStackBase = OrigStackBase;
1269 if (DoStackMalloc) {
1270 LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
1271 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1274 // This string will be parsed by the run-time (DescribeStackAddress).
1275 SmallString<2048> StackDescriptionStorage;
1276 raw_svector_ostream StackDescription(StackDescriptionStorage);
1277 StackDescription << F.getName() << " " << AllocaVec.size() << " ";
1279 // Insert poison calls for lifetime intrinsics for alloca.
1280 bool HavePoisonedAllocas = false;
1281 for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) {
1282 const AllocaPoisonCall &APC = AllocaPoisonCallVec[i];
1283 IntrinsicInst *II = APC.InsBefore;
1284 AllocaInst *AI = findAllocaForValue(II->getArgOperand(1));
1286 IRBuilder<> IRB(II);
1287 poisonAlloca(AI, APC.Size, IRB, APC.DoPoison);
1288 HavePoisonedAllocas |= APC.DoPoison;
1291 uint64_t Pos = RedzoneSize();
1292 // Replace Alloca instructions with base+offset.
1293 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1294 AllocaInst *AI = AllocaVec[i];
1295 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1296 StringRef Name = AI->getName();
1297 StackDescription << Pos << " " << SizeInBytes << " "
1298 << Name.size() << " " << Name << " ";
1299 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1300 assert((AlignedSize % RedzoneSize()) == 0);
1301 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1302 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1304 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1305 AI->replaceAllUsesWith(NewAllocaPtr);
1306 Pos += AlignedSize + RedzoneSize();
1308 assert(Pos == LocalStackSize);
1310 // Write the Magic value and the frame description constant to the redzone.
1311 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1312 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1314 Value *BasePlus1 = IRB.CreateAdd(LocalStackBase,
1315 ConstantInt::get(IntptrTy,
1317 BasePlus1 = IRB.CreateIntToPtr(BasePlus1, IntptrPtrTy);
1318 GlobalVariable *StackDescriptionGlobal =
1319 createPrivateGlobalForString(*F.getParent(), StackDescription.str());
1320 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1322 IRB.CreateStore(Description, BasePlus1);
1324 // Poison the stack redzones at the entry.
1325 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1326 poisonRedZones(AllocaVec, IRB, ShadowBase, true);
1328 // Unpoison the stack before all ret instructions.
1329 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1330 Instruction *Ret = RetVec[i];
1331 IRBuilder<> IRBRet(Ret);
1332 // Mark the current frame as retired.
1333 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1335 // Unpoison the stack.
1336 poisonRedZones(AllocaVec, IRBRet, ShadowBase, false);
1337 if (DoStackMalloc) {
1338 // In use-after-return mode, mark the whole stack frame unaddressable.
1339 IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
1340 ConstantInt::get(IntptrTy, LocalStackSize),
1342 } else if (HavePoisonedAllocas) {
1343 // If we poisoned some allocas in llvm.lifetime analysis,
1344 // unpoison whole stack frame now.
1345 assert(LocalStackBase == OrigStackBase);
1346 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1350 // We are done. Remove the old unused alloca instructions.
1351 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1352 AllocaVec[i]->eraseFromParent();
1355 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1356 IRBuilder<> IRB, bool DoPoison) {
1357 // For now just insert the call to ASan runtime.
1358 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1359 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1360 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1361 : AsanUnpoisonStackMemoryFunc,
1365 // Handling llvm.lifetime intrinsics for a given %alloca:
1366 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1367 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1368 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1369 // could be poisoned by previous llvm.lifetime.end instruction, as the
1370 // variable may go in and out of scope several times, e.g. in loops).
1371 // (3) if we poisoned at least one %alloca in a function,
1372 // unpoison the whole stack frame at function exit.
1374 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1375 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1376 // We're intested only in allocas we can handle.
1377 return isInterestingAlloca(*AI) ? AI : 0;
1378 // See if we've already calculated (or started to calculate) alloca for a
1380 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1381 if (I != AllocaForValue.end())
1383 // Store 0 while we're calculating alloca for value V to avoid
1384 // infinite recursion if the value references itself.
1385 AllocaForValue[V] = 0;
1386 AllocaInst *Res = 0;
1387 if (CastInst *CI = dyn_cast<CastInst>(V))
1388 Res = findAllocaForValue(CI->getOperand(0));
1389 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1390 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1391 Value *IncValue = PN->getIncomingValue(i);
1392 // Allow self-referencing phi-nodes.
1393 if (IncValue == PN) continue;
1394 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1395 // AI for incoming values should exist and should all be equal.
1396 if (IncValueAI == 0 || (Res != 0 && IncValueAI != Res))
1402 AllocaForValue[V] = Res;